In the past the failure point of electronically scanned arrays has been computed by ratioing the number of failed modules in the array to the total number of modules. This method provided a straight percentage which was selected to account for the occurrence of coordinated module failures, as well as randomly occurring module failures, and this percentage did not weight the location of the failures. In accordance with this invention, we provide weighting factors for the failed modules by accounting for the size and the location of the detected failures.
The prior art includes the following:
______________________________________ U.S. Pat. No. Inventor(s) ______________________________________ 4,926,186 Kelly et al 4,176,354 Hsiao et al ______________________________________
Kelly et al and Hsiao et al are each concerned with monitoring the operability or performance of phased array antenna systems. The Kelly et al method involves sampling the radiated beam by means including a single receiver and at non-uniform intervals of time during a beam scan, analyzing the samples to provide amplitude and phase values, and comparing same with design values to reveal elements or phase shifters which may be faulty.
Hsiao et al disclose a method which involves feeding a portion of radiated signals to a manifold network which combines them with signals symmetrically located with respect to the center of the array so that they differ by 180 degrees at the single manifold output. The output is then adjusted to zero by addition of radio frequency energy and the phase-shift settings of pairs of radiating elements having equal amplitude-weighting varied from the initial settings through 360 degrees. Failures are located by correlating the phase-shift settings and the adjusted output of the manifold network.
None of the prior art patents are concerned with the inventive features of defining failures, by assessing a severity weight to each module location in the array, totalling the score for all failures, and comparing the total to a threshold to determine if maintenance is warranted.